The present invention relates generally to photographic copying apparatus, and is more particularly concerned with apparatus for copying X-ray negative films on an underlying sensitized film by a controlled time exposure to a source of light rays. 2
Having reference to the prior art patents noted above, it will be seen that it has been generally known to provide a light chamber containing a light source from which light rays are conducted through a window or diffusing screen to a film negative which is held in contact with a sensitized film which is thus exposed for a predetermined time interval. Such procedure is conventional and well known in the photographic industry.
The known prior art structures differ primarily in the structural arrangement of the device or apparatus for carrying out such photographic procedures, and in the main differ primarily in the manner in which the film negative that is to be copied is maintained in pressure contact engagement with the sensitized film while being subjected to light rays emanating from the light source contained in an associated light chamber.
In general, the prior art devices have embodied rather complicated structures which are expensive to manufacture, and embody relatively complicated procedures in use.
In the photographic copying apparatus of U.S. Pat. No. 2,674,933, a box-like structure contains a light chamber having a top transparent platen upon which the drawing, film or the like is placed with an overlying sheet of photographic paper which are maintained in pressure contact by a spring pressed pressure pad carried by a hinged cover, when swung to closed clamped position.
The U.S. Pat. No. 3,067,666 discloses apparatus for overhead projection slides in which an assemblage of the film to be exposed is inserted through a slot in the light chamber, and entails the use of a complex compression assembly mechanism for holding the film sheets in registration, and roller bearing members which permit this mechanism to be inserted and removed through the slot.
U.S. Pat. No. 3,630,614 discloses a copying machine for documents using a heat and light process, and utilizing a cabinet removably mounted on a base, the cabinet providing a light chamber having an open face with a flat transparent rigid cover. The cabinet is hinged at one edge to the base which is held to the cabinet by means of rear hinges and a front clasp. The base is covered with a soft compressible sponge layer so that, when an original and a light sensitive intermediate is placed upon the base and the cabinet is lowered into position against the composite, the transparent plate will force the intermediate into close uniform pressure contact with the original against the compressible layer. As thus arranged, the exerted pressure is dependent upon the pressure of compressibility of the compressive layer.
U.S. Pat. No. 3,765,762 discloses an arrangement in which a light sensitive sheet is clamped between a flat translucent exposure surface and a foam rubber pad on the inner surface of a hinged top cover or lid for producing a uniform contact against the exposure surface. The top lid is provided with magnets or a pair of clamps with eccentrics to hold the lid in its closed position.
U.S. Pat. No. 4,343,549 discloses a box-type contact printer for photographic plate making, in which a lower frame and upper frame of transparent material are pivotally connected at their rear ends so that a photosensitive material and an original picture put thereon may be positioned between the two frames, and a shield box for covering the frames includes an exposure light source and a front opening adapted to be covered by a roll-up curtain. Provision is made for clamping the pivoted frames in closed position.
Briefly, the present invention seeks to provide a simplified and easily operable low cost film copying apparatus with a four-sided frusto-pyramidal housing structure which is fabricated to provide a light chamber having a bottom light transmitting window, which is hingedly connected to a flat base member provided with an upper surface of a soft compressible material. The base member is hingedly connected at one edge to one side of the housing structure for tilting movement thereof to an open position to enable the placement of a sensitized film and superposed film negative on the compressible material of the base member, and to a closed position with the light transmitting window overlying and pressing against the film negative to hold the film negative and the sensitized film in engagement during exposure.
The copying apparatus of the present invention embodies a number of desirable operating advantages and features, including the following:
a. Spring-biased platens and pressure plates, as used in the prior art structure, have been eliminated, and the inherent weight of the housing structure is utilized to hold the sensitized film and a superposed film negative in engagement during exposure to the light rays.
b. Another important feature resides in the utilization of a unique floating hinge connection between the housing structure and the base member, whereby the weight of the housing structure will be uniformly applied to the film negative and the operably associated sensitized film.
c. The housing structure has a four-sided frustro-pyramidal configuration and comprises an outer housing formed from a folded sheet of plastic material and an inner housing of a light reflecting metal, and which are secured in nested relation and coact to provide a light chamber. When the housing structure is moved to a tilted open position with respect to the hingedly connected base member, there is a tendency for the base member to be lifted at its hinged connected edge. This action is prevented by the provision of suitably placed bumpers in spaced relation to the hinged edge of the housing structure.